Toward Transportation Digital Twin Systems for Traffic Safety and Mobility: A Review

Digital twin (DT) systems aim to create virtual replicas of physical objects that are updated in real-time with their physical counterparts and evolve alongside the physical assets throughout their lifecycle. DT technology promises to significantly enhance the capabilities of intelligent transportation systems (ITSs) through improving safety and mobility. The objectives of this review article are to: 1) conduct an in-depth review of DT technology applications in the transportation domain, i.e., safety and mobility applications; 2) develop a reference architecture for a transportation DT (TDT) system based on a hierarchical concept to guide in developing TDT systems at any scale; 3) identify research challenges for each component, i.e., the physical space, the communication gateway and the digital space of the TDT system, to realize safe and operationally efficient ITS; and 4) provide future research perspectives to develop and deploy networkwide transportation DT systems considering the scale and dynamic nature of future connected and automated transportation systems. Thus, this article focuses on providing a comprehensive understanding of the requirements, reference architecture, challenges, and future research opportunities for a TDT system, starting from individual transportation assets and building up to the entire networkwide TDT.